This section provides background information related to the present disclosure which is not necessarily prior art.
Electrical systems within vehicles, such as hybrid, electric, and fuel cell vehicles, have advanced in complexity and power usage. Such vehicles can use an electric motor in combination with a battery power source. The battery can power the vehicle alone or can work in conjunction with another power source, such as an internal combustion engine.
High power output and large capacity batteries can be used as the battery power source. A number of battery cells can be connected in series or parallel with each other so as to construct a larger battery assembly. The battery cells can be packaged together with various mechanical and electrical couplings between the battery cells to form the assembly. One type of battery assembly includes prismatic batteries or pouch-shaped batteries placed in a stacked relationship to reduce space and overall size of the assembly. For example, lithium-ion battery cells can be formed as prismatic battery cells that utilize a pouch filled with a liquid or a polymer electrolyte. Such prismatic battery cells can exhibit changes in thickness during charging/discharging and over a lifetime of the cells. For example, each battery cell pouch can swell or contract, effecting a change in one or more dimensions of the battery cells and battery assembly.
Heat can be generated by the battery cells during a charging process and a discharging process. Heat that accumulates in the battery assembly can adversely affect the battery cells. Accordingly, a cooling system can be provided to maintain a desirable operating temperature. Such cooling systems can include some manner of heat sink or fluid heat exchanger where air is blown over the battery cells and/or a liquid coolant is used. For example, a cooling system can include one or more cooling plates or fins sandwiched between individual battery cells within the battery assembly. In some cases, the cooling system can have channels through which a fluid (e.g., coolant) flows in a heat transfer relationship with the battery cells.
The temperature of a battery cell in a battery assembly is an important factor related to the serviceable life and performance of the battery. As battery assemblies can have many battery cells stacked together, temperature can be different at different locations in the assembly. Moreover, individual battery cells can vary in performance and hence operating temperature due to variations in manufacture. Thus, there is a need for accurate determination of the temperature of a battery cell, including the multiple battery cells within a battery assembly.